Bike Fitting using Motion Analysis

Just did some DIY bike fitting at home over the weekend, after viewing almost all the bike fitting clips in YouTube. Saw one of the clips in YouTube, stating how they used motion analysis to do bike fitting/analysis. Just nice, Grace who has trainer, is going to Port Dickson over the weekend for race. So borrowed the trainer, hook up my camera and ACTION!

Riding on a new bike again, confused with the bike fitting theories recommended by different people. So decided to film myself to see how i look like while riding instead of hearing people's comments. Perspective can be different from view's of different people, which leads to the wrong buy of my titanium frame.

Currently judging by personal comfort, going for longer rides to see which area needs to improve. But worried that my current 'comfort' position might be straining my knees, or not optimizing my effort when riding.

Google online, looking for 'ideal' leg bend angles, poseur etc... Trying to find the commonly used figures.

Upper body Poseur

Looks pretty decent to me, not to upright nor to forward.. Looks like I'm tipping toes when pedal is at 6 o'clock (had lowered seat by 5mm)

Leg Bend Angle

As said earlier, googled on leg angle. Mostly recommend 30-35 deg. I don't know how they get that figure. What i assumed is the difference in angle when knee is bent from a straight poseur.
The above picture is not very accurate, forget to paste a sticker over my pelvis bone. So have to estimate the point.

Knee Over Pedal

This is to check the fore/aft of the saddle. Looks fine to me. Except on a few occasions, my knees will move forwards by 1-2cm. On a clip showing bike fit for tri bikes, they figured this guy with 3-4cm knee in front of the pedal spindle. So i think its fine, anyway i don't always move forward.

Overall was glad that i can see how i ride and some figures regarding my current position. Problem with using motion analysis is the camera angle and position of it from the user. The areas away from the camera focus point tend to convex out. Still cant beat bike fitting with the help of a friend doing the measuring while you cycle.

Sorry, didnt wanna go throught the features of the software im using. Pretty tired of drafting this post already. The only main features is, it can slowdown and pause split-seconds of your action and take measurements.


Bike Fit Anatomy
C Cube